A known shears-like vehicle jack of this kind has a foot plate as the foot member, which is mounted upon the leg by a hinge. For safer support of the jack, the foot plate should always rest flat upon the ground. Because of the hinge joint, the necessarily inclined position of the leg on installation is not always well defined, so that with an improperly inclined position, slipping of the jack can occur on lifting.
Known spindle jacks with rigid carrier arms have a roller foot mounted on the leg. Apart from its support surface, this has a contact surface provided at an angle, with which the desired inclined position of the leg can be determined on installation of the jack under the vehicle. It has already been shown that slipping of even this jack can occur, particularly with modern powered vehicles with monocoque bodywork. This is because of unsuitable inclined positions of the strut made necessary by this type of body for the different heights of the vehicle at the beginning of lifting.